Chimpanzees: Observational Study

For centuries, humans have evolved and developed complex familial systems, uses of tools for survival, and a sense of right and wrong. Humans, or Homo sapiens, are animals that have evolved from ancestors closely related to the nonhuman primates that are seen today. Several distinctive characteristics separate humans from other primate relatives and other vertebrates, such as possessing a bipedal gait and erect posture, as well as having the largest brain relative to body mass and a far more advanced cerebral cortex (Kim, Martinez, Choe, Lee, & Tomonaga 2015). However, an increasing number of studies and researchers suggest that prosocial behaviors that are seen in humans can be observed in nonhuman primates that live in complex social groups.

Although there are few observational studies done that mainly address altruistic behaviors in wild chimpanzees, it has been observed that under the correct socio-ecological conditions, chimpanzees have cared for the welfare of seemingly unrelated (or not closely related) group members. In one observational study conducted at the Chester Zoo in the United Kingdom, cooperative behavior of group of captive chimpanzees, consisting of five adult males, twelve adult females, six subadult females, one juvenile female, two male infants and one female infant, was documented and analyzed (Bethell & Waller, 2004). The female infant chimpanzee, named Kirsty, was seen crouching and leaning forward to drink from a moat. Another chimpanzee, a juvenile female named Pattie, shoved Kirsty into the moat and ran away, causing the other members of the group to vocalize and move about the enclosure. None of the adults or larger chimpanzees came to the aid of Kirsty, despite her mother Alice being three meters away, and the young infant made no attempts to climb out (Bethell & Waller, 2004). Chimpanzees After witnessing the young chimp struggle in the water, Boris, a former alpha

In terms of biological altruism, Boris’s actions to save Kristy may have been situational evidence of the theory of cooperation through kin selection, known as Hamilton’s rule, developed by W. D. Hamilton. Kin selection states that an organism aids another in order to increase its reproductive success, even at the cost of its own reproductive success or even survival. In addition, Hamilton’s rule explains that aid-giving behavior can occur when the indirect fitness (or the measure of genetic success of an altruistic organism based on the number of relatives it helps reproduce that otherwise might not have survived without aid) benefits of aiding relatives compensates the altruist for any personal reproductive losses (Okasha, 2003). Through further genetic testing, it was determined that Boris was likely Kirsty’s maternal grandfather (Bethell & Waller, 2004), which could therefore explain that Boris was acting to increase his inclusive fitness, or his overall success in passing on his genetic material. Moreover, this act of directed altruism may have come about due to Frans de Waal’s idea of an “altruistic impulse”. Boris’s act of kindness may have been a spontaneous, disinterested caring reaction to the distress signals of Kirsty in the water (de Waal, 2008). While this may be difficult to prove empirically, experts